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M7IQ1- Causes and Transmission - Coggle Diagram
M7IQ1- Causes and
Transmission
Types of
Pathogens
Microorganism
(non-cellular)
Viruses
non-cellular
contains a protein outer case that protects internal nucleic acid (DNA or RNA)
requires the cells of their host for reproduction: penetrates organisms defences, sheds protein coat and releases DNA/RNA into host cells.
eg: ebola, influenza, sars-cov 19
Prions
non-cellular protein
cause neurodegenerative diseases in human and other animals by promoting abnormal folding of proteins in the host's nervous system
eg: malaria, leishmaniasis
Macroorganisms
Endoparasites
a parasite (eg: tapeworm) that lives inside its host
generally have a longer association with its host organism
Ectoparasites
a parasite (eg: flea) that lives on the outside of its host
normally has a shorter association with its host organism
Microorganism
(cellular)
Fungi
uni/multicellular eukaryotes
secretes enzymes and other matter to break down organic matter. has a cell wall with DNA in a nucleus.
eg: athlete's foot, ringworm
Protists
unicellular eukaryote
protozoa (animal-like), algae (plant-like), slime moulds (fungi-like)
no cell wall, contains structures to aid mobility
eg: malaria, leishmaniasis
Bacteria
unicellular prokaryote.
contains cell walls, DNA but no nucleus. has structures to aid in mobility.
eg: meningitis, e.coli
Transmission
of Disease
Indirect Contact
occurs when the host and another organism have no direct contact with each other (reservoir or a vector)
means include: airborne, contact with infected surface, contaminated food/water, infected surgical equipment, vectors.
eg: measles, influenza (droplets), e.coli (food)
Vectors
living organisms that can
transmit infectious diseases
between two organisms
(mainly bloodsucking insects)
eg: malaria, leishmaniasis,
canine/feline heartworm
the way a pathogen spreads disease from one host to the next; infected to non-infected.
expose does not = infection. susceptibility is based on host genetics, immunity and health.
portal of exit:
pathway a pathogen takes to exist a host (cough, body fluids, etc)
portal of entry:
same as portal of exit. pathogen must be able to access tissue where it can grow and reproduce.
Direct Contact
physical contact between host and non-infected organism.
horizontal transmission:
contact between organisms of the same generation (not parent-child).
vertical transmission:
contact between parent and offspring (childbirth)
eg: ringworm, HIV, Herpes simplex virus
Koch's
Postulates
principles used to identify
the specific microorganism that
is responsible for a disease. first
discussed in 1877.
1.
the same microorganism must be present in every diseased host
2.
the microorganism must be isolated and cultured in the lab and accurately described and recorded
3.
when a sample of the pure culture is inoculated into a healthy host, this host must develop the same symptoms as the original host
4.
the microorganism must be able to be isolated from the second host and cultured and identified as the same as the original species
Pasteur's
Experiments
germ theory of disease: proved that organisms that contaminated the broth must be carried in the air and not be spontaneously generated.
involved boiling meat broth in two swan necked flasks, one intact, and one with the curved neck breaking off.
as the broth cooled, the air is drawn in from the outside. any microorganisms present in the air did not reach or contaminate the broth in the intact flask, as they were trapped in the narrow curved neck.
bacterial growth occurred in the broken flask as the contents were exposed to microorganisms in the air
Disease and
Agriculture
many plants and animals have been artificially selected or cloned for particular traits, making them more susceptible to disease due to
loss of genetic diversity
.
intensive farming practices
puts plants and animals in closer proximity than before, increasing the risk of pathogen transmission.
Notes
disease
can be defined as 'any condition that adversely affects the normal functioning of any part of a living thing.'
an
infectious disease
is caused by another organism or pathogen.
endemic
: a disease that exists permanently in a particular region or population
outbreak
: number of cases that exceeds what would be expected
epidemic
: an outbreak of disease that attacks many people at around the same time and may spread through one or several communities
pandemic
: when an epidemic spreads throughout the world